Hi!
Thank you for your feedback; it is a little late to fix/tweak this, since Polymute's probably not going to be getting much in the way of future updates at this point (in fact I've released a whole other game since releasing this! Time sure flies). Still, I appreciate the difficulty being brought to my attention, and I'll try to make my future projects more lenient.
I'm not sure if this will help at all, but as a note, the boss "timer" pauses when in the menu, meaning you have as much time as you'd like while in there to try to figure out what to turn into, though if that doesn't help Youtubing the ending is certainly an option too.